import math
x1, y1, x2, y2 = map(float, input().split())
x3 = x2 - x1
y3 = y2 - y1
ans = math.hypot(x3, y3)
print(ans) import math math x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 x3 = x2 - x1 x3 x2 - x1 x2 x1 y3 = y2 - y1 y3 y2 - y1 y2 y1 ans = math.hypot(x3, y3) ans math.hypot(x3, y3) math.hypot math hypot x3 y3 print(ans) print ans x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1 y2 = map(float, input().split()) map(float, input().split()) y2 y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1 x3 = x2 - x1 x2 - x1 x3 y3 = y2 - y1 y2 - y1 y3 x2, y2 = map(float, input().split()) map(float, input().split()) x2 ans = math.hypot(x3, y3) math.hypot(x3, y3) ans
import math
x1, y1, x2, y2 = map(float, input().split())
x3 = x2 - x1
y3 = y2 - y1
ans = math.hypot(x3, y3)
print(ans)
